There are methods well-known in the art for providing RF communication services among groups of users. One such familiar method is the conventional simulcast system. A conventional simulcast system usually comprises several communication sites, each of which has the capability to cover a fairly wide area. Each of these sites contains one or more repeater stations. A repeater station is a type of fixed communication unit that is designed to receive signals on one frequency and re-transmit the same signals on another frequency, generally at a higher power. This concept is particularly useful in improving system coverage when it is desired to communicate with a relatively large number of users that may be located in any one of the several sites comprising the simulcast system. All the repeater units are activated simultaneously, on the same frequency, thus broadcasting the desired information over a wide area.
Trunked communication systems can also provide wide area communication service to specific groups of users. Since trunked communications employ both user IDs (identifications) and group IDs, messages intended for single users or groups of users can be transmitted over a multi-site trunked system with relative ease.
One problem shared by both trunked systems and conventional simulcast systems is efficient allocation of RF frequencies, or communication resources, to communication units within their respective systems. In conventional simulcast, since a repeater station within each site is activated for a specific group call transmission, that frequency cannot be used for any other purpose within any of the sites that have been activated. In present-day trunking systems, even though the frequency used in each site of a multi-site system need not be the same, a repeater station must still be activated in each one of the sites.
Accordingly, a need arises for a method for allocating communication resources within a multi-site trunked radio system that does not needlessly encumber communication resources.